Virus Circulation Research Articles

Seasonal Shifts in Influenza, Respiratory Syncytial Virus, and Other Respiratory Viruses After the COVID-19 Pandemic: An Eight-Year Retrospective Study in Jalisco, Mexico

The coronavirus disease 2019 (COVID-19) pandemic profoundly disrupted the epidemiology of respiratory viruses, driven primarily by widespread non-pharmaceutical interventions (NPIs) such as social distancing and masking. This eight-year retrospective study examines the seasonal patterns and incidence of influenza virus, respiratory syncytial virus (RSV), and other respiratory viruses across pre-pandemic, pandemic, and post-pandemic phases in Jalisco, Mexico. Weekly case counts were analyzed using an interrupted time series (ITS) model, segmenting the timeline into these three distinct phases. Significant reductions in respiratory virus circulation were observed during the pandemic, followed by atypical resurgences as NPIs were relaxed. Influenza displayed alternating subtype dominance, with influenza A H3 prevailing in 2022, influenza B surging in 2023, and influenza A H1N1 increasing thereafter, reflecting potential immunity gaps. RSV activity was marked by earlier onset and higher intensity post-pandemic. Other viruses, including human rhinovirus/enterovirus (HRV/HEV) and parainfluenza virus (HPIV), showed altered dynamics, with some failing to return to pre-pandemic seasonality. These findings underscore the need for adaptive surveillance systems and vaccination strategies to address evolving viral patterns. Future research should investigate the long-term public health implications, focusing on vaccination, clinical outcomes, and healthcare preparedness.

Dengue virus transmission in Italy: historical trends up to 2023 and a data repository into the future

Dengue virus circulation is on the rise globally, with increased epidemic activity in previously unaffected countries, including within Europe. In 2023, global dengue activity peaked, and Italy reported the highest number of dengue cases and local chains of transmission to date. By curating several sources of information, we introduce a novel data repository focused on dengue reporting in Italy. We integrate data from such a repository with other geographic, genomic and climatic spatiotemporal data to present an overview of transmission patterns of the past eight years related to circulating viral lineages, geographic distribution, hotspots of reporting, and the theoretical contribution of local climate. The novel data repository can contribute to a better understanding of an evolving epidemiological scenario in Italy, with the potential to inform reassessment and planning of adequate national and European public health strategies to manage the emergence of the dengue virus.

Measuring transboundary disease spread - ASF in wild boars straddling Piedmont and Liguria

The aim of this paper is to describe the impact, dynamics and risk factors of the incursion of the African Swine Fever (ASF) virus detected in early 2022 in the wild boar population straddling Piedmont and Liguria, 24 months after its emergence.A study area of 4,162.2 square kilometres, comprising 234 municipalities in Liguria and Piedmont (north-western Italy), along with an external buffer zone, was considered. The epidemiological units were wild boars tested for ASF using real-time PCR between late December 2021 and December 31, 2023. The data were obtained from passive and active surveillance. Conventional methodologies were applied in the analysis of time series of tests, cases, or prevalence rates of positive animals. Maps were used to visualise and compare the monitoring activities, the location of cases and municipal standardised prevalence ratios. Clustering of high and low trends was studied by semester using a space-time permutation model. Risk factors analysis was based on multivariate Poisson regression modelling.Over the 2-year study period, the epidemic's spread was closely monitored by testing 10,412 wild boars (25% of them from passive surveillance). Probability of disease detection was 10.9 times higher among found dead animals compared with animals tested in active surveillance. Difficulties in carcass searching led to heterogeneities in surveillance sensitivity achieved locally and inherent uncertainties. A total of 1,165 wild boars that tested positive for ASF have been detected in 125 municipalities across three provinces. The outbreak has expanded over time and exhibited an increasing trend, with an epidemic doubling time of 10.7 months. There was seasonality, with an increasing trend from summer to spring. Prevalence rates followed the same temporal pattern. Significant low and high clusters respectively indicated endemic episodes in the interior areas of virus circulation and an ongoing invasion of surrounding regions.The characteristics of this outbreak align with the cycle of wild boar habitat transmission observed in other outbreaks across Europe. The measures implemented were not sufficient to stop the epidemic: however, targeted interventions such as depopulation campaigns, reinforcement of physical barriers and increased biosecurity measures have prevented local spillover to domestic pigs and partially hindered the advance of the disease. In addition, the shown seasonality of the disease, likely can enhance control measures. The ongoing studies of the local wild boar populations and the evolution the epidemic along with the lessons learned so far will improve the efficiency and effectiveness of efforts to limit and ultimately eradicate the disease.

Silent St. Louis encephalitis virus circulation evidence by a haemovigilance survey in a centralized blood bank.

Saint Louis encephalitis virus (SLEV) re-emergence and its geographical expansion, evidenced by its emergence in previously unaffected areas, have raised significant public health concerns. We aimed to show the usefulness of haemovigilance as an effective tool to fill arboviruses surveillance gaps to track trends and identify hotspots. Within the framework of a blood bank haemovigilance program, we performed a survey to evaluate the potential threat of circulating mosquito-borne infections for transfusion safety. SLEV was detected by a PCR targeting the conserved NS5-gene region, and the PCR-product was subjected to direct nucleotide sequencing reaction. The SLEV-strain detected in the blood donor (OR236721) clustered with previously reported CbaAr-4005, 79V-2533, and MN413675 isolated in Córdoba (2005, epidemic), Santa Fe (1979, non-epidemic) and Buenos Aires (2013, non-epidemic), with 97% identity. Herein, we show the usefulness of haemovigilance in uncovering the silent circulation of arboviral infections. Implementing this systematic surveillance approach would allow for monitoring the distribution and incidence of vector-borne diseases, providing information that could prevent the spread of the virus and its introduction into novel biomes. Ultimately, leveraging haemovigilance enables timely identification of potential outbreaks and empowers policymakers to make well-informed decisions to safeguard public health.

Comprehensive Molecular Epidemiology of Influenza Viruses in Brazil: Insights from a Nationwide Analysis

Abstract Influenza A and B viruses represent significant global health threats, contributing substantially to morbidity and mortality rates. However, a comprehensive understanding of the molecular epidemiology of these viruses in Brazil, a continental-size country and a crucial hub for the entry, circulation, and dissemination of Influenza viruses within South America, still needs to be improved. This study addresses this gap by consolidating data and samples across all Brazilian macroregions, as part of the Center for Viral Surveillance and Serological Assessment (CeVIVAS) project, together with an extensive number of other Brazilian sequences provided by a public database during the epidemic seasons spanning 2021-2023. Phylogenetic analysis of the Hemagglutinin segment (HA) of Influenza A/H1N1pdm09, A/H3N2, and Influenza B/Victoria-lineage revealed that in 2021 and in the first semester of 2022 the A/H3N2 2a.3 strain was the predominant circulating strain. Subsequently, the A/H3N2 2b became the prevalent strain until October, when it was substituted by A/H1N1pdm09 5a.2a and 5a.2a.1 lineages. This scenario was maintained during the year of 2023. B/Victoria emerged and circulated at low levels between December 2021 and September 2022, then became co-prevalent with A/H1N1pdm09 5a.2a and 5a.2a.1 lineages. The comparison between the vaccine strain A/Darwin/9/2021 and circulating viruses revealed shared mutations to aspartic acid at residues 186 and 225 across all A/H3N2 lineages from 2021 to 2023, altering the charge in the RBD domain. For A/H1N1pdm09, the 2022 consensus of 5a.2a.1 and the vaccine strain A/Victoria/2570/2019 showed 14 amino acid substitutions. Key residues H180, D187, K219, R223, E224, and T133 are involved in hydrogen interactions with sialic acids, while N130, K142, and D222 may contribute to distance interactions based on docking analyses. Importantly, distinct Influenza A lineage frequency patterns were observed across Brazil’s macroregions, underscoring the regional variations in virus circulation. This study characterizes Influenza A and B viruses circulating in Brazil, providing insights into their circulation patterns and dynamics across Brazilian macroregions. These findings hold significant implications for public health interventions, informing strategies to mitigate transmission risks, optimize vaccination efforts, and enhance outbreak control measures.

Cross-neutralization of Influenza A by SARS-CoV-2 specific neutralizing antibodies and polyclonal plasma: Is pre-exposure to SARS-CoV-2 protective against Influenza A?

According to sparse information from various countries, the seasonal influenza virus circulation has drastically decreased during the COVID-19 pandemic. Here, we show the cross-reactivity of anti-SARS-CoV-2 antibodies against influenza viruses. Plasma samples were collected from 311 SARS-CoV-2 infected individuals. The samples were tested for antibody titers against SARS-CoV-2 by ELISA and seasonal influenza virus strains (influenza A/H1N1, A/H3N2, B/Yamagata, and B/Victoria) using a Hemagglutination Inhibition Assay (HAI). In addition, SARS-CoV-2 antibody-positive but Influenza antibody-negative samples (n = 16) were investigated to determine the SARS-CoV-2 antibody-neutralizing potential against influenza viruses by microneutralization (MN) assay. The SARS-CoV-2 genomes were sequenced using Illumina next-generation sequencing, and an in-silico protein structural analysis was performed to identify epitope and antibody binding similarities between SARS-CoV-2 and influenza viruses. Among 16 samples that didn't contain antibodies against Influenza A strains (H1N1 and H3N2), five showed high (MN titer≥20), and six showed moderate (MN titer≥10) capability to neutralize Influenza A. Subsequent in-silico analysis revealed that most efficient binding (>8 kcal/mol) was found between the antibodies of SARS-CoV-2 delta variant (ΔG) with influenza A/H1N1 HA (Hemagglutinin), A/H3N2 HA, A/H1N1 NA (Neuraminidase), and A/H3N2 NA glycoproteins with −12.4, −9.3, −10.1, and −11.7 kcal/mol, respectively. This investigation revealed that neutralizing antibodies of the delta variant cross-reacted with the Influenza A virus, which might protect against influenza viruses and reduce and shift the seasonal influenza circulation during the COVID-19 pandemic. Our findings warrant further study to explain the probable mechanisms of this cross-reactivity.

Evidence of Zika virus circulation in human and livestock in Chad

Zika virus (ZIKV) is a major public health problem worldwide. After several reported outbreaks, the current extent of infections caused by this orthoflavivirus in the Sahel remains to be explored. We investigated the prevalence of neutralizing antibodies against ZIKV in the general population, in HIV-infected individuals and in livestock in Chad using a seroneutralization assay that ensures high specificity level. In this retrospective serological serosurveillance investigation, we estimated the neutralizing seroprevalence to be approximately 26 % (18/69) in healthy Chadian participants and 17 % (16/94) in HIV-infected individuals, with no statistical difference between these two subgroups or genders. In addition, we found an overall ZIKV prevalence of 14 % (8/59) in small ruminants (sheep and goats) living in the Lake Chad Basin area, demonstrating virus circulation in animals. Our pilot study shows for the first-time evidence of ZIKV circulation in humans and in livestock in Chad in close interaction with humans, and highlights the main challenges associated with this virus in Sahelian areas.

Characterizing the interactions between influenza and respiratory syncytial viruses and their implications for epidemic control.

Pathogen-pathogen interactions represent a critical but little-understood feature of infectious disease dynamics. In particular, experimental evidence suggests that influenza virus and respiratory syncytial virus (RSV) compete with each other, such that infection with one confers temporary protection against the other. However, such interactions are challenging to study using common epidemiologic methods. Here, we use a mathematical modeling approach, in conjunction with detailed surveillance data from Hong Kong and Canada, to infer the strength and duration of the interaction between influenza and RSV. Based on our estimates, we further utilize our model to evaluate the potential conflicting effects of live attenuated influenza vaccines (LAIV) on RSV burden. We find evidence of a moderate to strong, negative, bidirectional interaction, such that infection with either virus yields 40-100% protection against infection with the other for one to five months. Assuming that LAIV reduces RSV susceptibility in a similar manner, we predict that the impact of such a vaccine at the population level would likely depend greatly on underlying viral circulation patterns. More broadly, we highlight the utility of mathematical models as a tool to characterize pathogen-pathogen interactions.

Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021-2024).

Influenza viruses continue to be an important public health threat. Vaccination is the most effective measure to control the influenza virus circulation. However, these viruses are continuously evolving through antigenic drift/shift, and thus the vaccine efficiency is affected. The aim of this study was to characterize the viral strains circulating in Romania, in a population with declining vaccination coverage, during the last three cold seasons by evaluating the hemagglutinin antigenic relatedness to the vaccine strains. All the available sequences collected between August 2021 and June 2024 were analyzed by using phylogenetic analysis and the Pepitope model to predict vaccine efficacy. The results showed that the 2021/2022 influenza season was dominated by the circulation of highly diverse clades of A(H3N2) viruses with high mutational divergence as compared to the vaccine strain, which might contribute to the reduction in vaccine efficacy. During the 2022/2023 influenza season, both influenza A and B viruses were reported, with few antigenic site mutations. The 2023/2024 influenza season was dominated by the circulation of influenza A viruses: A/H1N1pdm09 clade 6B.1A.5a.2a and A/H3N2 clade 2a.3a.1. The clade 2a.3a.1 also showed high variability when compared to the vaccine strain, presumably leading to reduced vaccine efficacy. This study illustrates the high diversity of influenza viruses circulating in a population with low vaccination coverage during the previous cold seasons. The viral diversity impacted vaccine efficacy, hence the need for public health programs to increase vaccine uptake and improve vaccine formulation in order to limit viral transmission.

Prevalence of Crimean-Congo Haemorrhagic Fever virus and Ganjam virus among livestock & ticks in Wayanad, Kerala.

The Western Ghat region of Kerala has abundant flora and domestic and wild animal species that provide an ideal ecological niche for the ticks. Kyasanur Forest Disease virus (KFDV), a zoonotic tick-borne virus causing Haemorrhagic fever, commonly known as monkey fever is prevalent in the area. The tick infestations have been documented in the majority of household animals in Wayanad and risks are further amplified as the majority of the animals reared, graze in the adjoining forest areas and these animals are often housed in and around farmer's dwellings. Therefore, the farmers are at high risk of contracting deadly tick-borne diseases, and surveillance in animals can act as an indicator of disease hotspots. Even though the tick-borne KFDV is endemic to the area, the surveillance data on other significant zoonotic tick-borne viruses such as CCHFV and GANV are scanty. Overall CCHFV seroprevalence of 2.33 was reported amongst livestock sampled. Species-wise percent seropositivity was 1.01 and 5.10 in cattle and goats, respectively. The study revealed the presence of ticks belonging to 3 genera viz. Rhipicephalus, Amblyomma, and Haemaphysalis. Despite the CCHFV seroprevalence, CCHFV and GANV could not be detected in ticks. Even though ticks were negative for the CCHFV genome, seroprevalence in adjoining taluks indicates the local virus circulation. Therefore serological as well as molecular investigation with a large number of samples collected at the peak of tick activity across the western ghat would help identify the potential hotspot for CCHFV.

Unravelling demographic and socioeconomic patterns of COVID-19 death and other causes of death: results of an individual-level analysis of exhaustive cause of death data in Belgium, 2020

BackgroundThe COVID-19 pandemic led to significant excess mortality in 2020 in Belgium. By using microlevel cause-specific mortality data for the total adult population in Belgium in 2020, three outcomes were considered in this study aiming at predicting sociodemographic (SD) and socioeconomic (SE) patterns of (1) COVID-19 specific death compared to survival; (2) all other causes of death (OCOD) compared to survival; and (3) COVID-19 specific death compared to all OCOD.MethodsTwo complementary statistical methods were used. First, multivariable logistic regression models providing odds ratios and 95% confidence intervals were fitted for the three study outcomes. In addition, we computed conditional inference tree (CIT) algorithms, a non-parametric class of classification trees, to identify and rank by significance level the strongest predictors of the three study outcomes.ResultsOlder individuals, males, individuals living in collectivities, first-generation migrants, and deprived SE groups experienced higher odds of dying from COVID-19 compared to survival; living in collectivities was identified by the CIT as the strongest predictor followed by age and sex. Education emerged as one of the strongest predictors for individuals not living in collectivities. Overall, similar patterns were observed for all OCOD except for first- and second-generation migrants having lower odds of all OCOD compared to survival; age group was identified by the CIT as the strongest predictor. Older individuals, males, individuals living in collectivities, first- and second-generation migrants, and individuals with lower levels of education had higher odds of COVID-19 death compared to all OCOD; living in collectivities was identified by the CIT as the strongest predictor followed by age, sex, and migration background. Education and income emerged as among the strongest predictors among individuals not living in collectivities.ConclusionsThis study identified important SD and SE disparities in COVID-19 mortality, with living in collectivities highlighted as the strongest predictor. This underlines the importance of implementing preventive measures, particularly within the most vulnerable populations, in infectious disease pandemic preparedness to reduce virus circulation and the resulting lethality.

Evolution and Impact of Hepatitis A Epidemiology in Europe-Systematic Literature Review of the Last 20 Years.

While globally hepatitis A (hepA) infections occur in 150 million people annually, European high-income countries now have a low endemicity. However, this results in a more susceptible adult population which is prone to severe illness. To determine current epidemiological characteristics, we performed a systematic literature review to assess the severity of hepA disease in the past two decades in 11 European countries (i.e., Denmark, France, Germany, Greece, Hungary, Italy, the Netherlands, Spain, Sweden, Switzerland and the United Kingdom). Literature search was performed using PubMed and Embase between 1 January 2001 and 14 April 2021. Search terms included the disease (hepA), the 11 selected countries, the term 'outbreaks' and its synonyms, outcomes and terms for hepA virus circulation. In total, 43 records reported data on hepA disease outcomes. Hospitalisation rates varied between the countries, with annual rates exceeding 50% at least once in seven countries. The lowest hospitalisation rates were reported for the Netherlands (≤ 32%) and the highest for Greece (≥ 81%). Liver failure, haemorrhagic and other complications were rarely reported, and case fatality rates were low (0.03%-0.26%). Our findings are consistent with the trends observed globally. This systematic literature review highlights the need to increase awareness of hepA risks and to strengthen prevention strategies. Continuous monitoring of epidemiological data is crucial to assess which populations would most benefit from prevention, mainly with respect to future vaccination recommendations.

Circulation of West Nile virus and Usutu virus in birds in Germany, 2021 and 2022

Background Usutu virus (USUV) and West Nile virus (WNV) are zoonotic arthropod-borne orthoflaviviruses. The enzootic transmission cycles of both include Culex mosquitoes as vectors and birds as amplifying hosts. For more than 10 years, these viruses have been monitored in birds in Germany by a multidisciplinary network. While USUV is present nationwide, WNV used to be restricted to the central-east. Methods In 2021 and 2022, over 2300 live bird blood samples and organs from over 3000 deceased birds were subjected to molecular and serological analysis regarding the presence of WNV and USUV. The samples were collected at sites all over Germany. Results Circulation of both viruses increased in 2022. For USUV, the nationwide presence of lineages Africa 3 and Europe 3 reported in previous years was confirmed. Lineage Europe 2, formerly restricted to the German east, was able to expand westward. Nonetheless, USUV neutralizing antibody (nAb) detection rates remained low (< 9%). Years 2021 and 2022 were characterized by stable enzootic circulation of WNV lineage 2, dominated by one previously identified subcluster (95% of generated sequences). In 2022, >20% of birds in the endemic region in eastern Germany carried nAb against WNV. Serological data also indicate expanding WNV circulation west and south of the known hotspots in Germany. Conclusions USUV circulates enzootically nationwide. Emergence of WNV at several new locations in Germany with a potential increase in human infections may be imminent. In this context, wild bird monitoring serves as a capable early warning system in a One Health setting.

Post-disappearance scenarios: policy implications following the potential disappearance of B/Yamagata lineage influenza viruses.

The COVID-19 pandemic and related preventive measures reduced influenza virus circulation, notably causing the disappearance of the B/Yamagata lineage of influenza viruses. In this Perspective, we discuss the implications that this development may have for global influenza epidemiology, and the adjustments that may need to be implemented concerning surveillance strategies and practices, laboratory safety protocols, and influenza vaccine formulations. The disappearance of the B/Yamagata lineage might indeed alter the dynamics of the influenza disease burden (although in a way that is difficult to predict at the moment), and associated diagnostic practices, and may also necessitate updated biosafety levels and revised influenza surveillance strategies. Furthermore, the World Health Organization (WHO) recommended in September 2023 the exclusion of B/Yamagata antigens from future vaccines, with a shift towards trivalent vaccines or modified quadrivalent vaccines; this new scenario underscores the importance of robust global respiratory virus surveillance, effective communication with healthcare professionals and the population to maintain trust in vaccines, and a collaborative approach among health policymakers and vaccine manufacturers to navigate this epidemiological change.

Adapting COVID-19 research infrastructure to capture influenza and respiratory syncytial virus alongside SARS-CoV-2 in UK healthcare workers winter 2022/23 and beyond: protocol for a pragmatic sub-study

Introduction During the COVID-19 pandemic, extensive research was conducted on SARS-CoV-2; however, important questions about other respiratory pathogens remain unanswered. A severe influenza season in 2022–2023 with simultaneous circulation of SARS-CoV2 and respiratory syncytial virus is anticipated. This sub-study aims to determine the incidence and impact of these respiratory viruses on healthcare workers, the symptoms they experienced, the effectiveness of both COVID-19 and influenza vaccination and the burden of these infections on the National Health Service (NHS) workforce. Methods and analysis This is a longitudinal prospective cohort sub-study, utilising the population and infrastructure of the SARS-CoV-2 Immunity &amp; Reinfection Evaluation (SIREN) study, which focuses on hospital staff in the UK. Participants undergo fortnightly nucleic acid amplification testing on a multiplex assay including SARS-CoV-2, influenza A and B and RSV, regardless of symptoms. Questionnaires are completed every two weeks, capturing symptoms, sick days, exposures, and vaccination records. Serum samples are collected monthly or quarterly from participants associated with a SIREN site. This sub-study commenced on 28/11/22 to align with the predicted influenza season and participants’ influenza vaccine status. The SIREN Participant Involvement Panel shaped the aims and methods for the study, highlighting its acceptability. UK devolved administrations were supported to develop local protocols. Analysis plans include incidence of asymptomatic and symptomatic infection, comparisons of vaccination coverage, assessment of sick day burden, and effectiveness of seasonal influenza against infection and time off work. Data are also integrated into UKHSA nosocomial modelling. Ethics and dissemination The protocol was approved by the Berkshire Research Ethics Committee (IRAS ID 284460, REC Reference 20SC0230) on 14/11/2022. Participants were informed in advance. As the frequency and method of sampling remained the same, implied consent processes were approved by the committee. Participants returning to the study give informed consent. Regular reports to advisory groups and peer-reviewed publications are planned to disseminate findings and inform decision making. Clinical trial registration number: ISRCTN11041050; registration date: 12 January 2021. Sub study included in protocol version: v8.0, and amended in v9.0

Distribution and abundance of Aedes caspius (Pallas, 1771) and Aedes vexans (Meigen, 1830) in the Po Plain (northern Italy).

Knowledge of the distribution and abundance of disease-causing mosquito vectors is fundamental for assessing the risk of disease circulation and introduction. Aedes caspius (Pallas, 1771) and Aedes vexans (Meigen, 1830) have been implicated, to different extents, in the circulation of several arthropod-borne viruses (arboviruses). These two mosquitoes are vectors of Tahyna virus in Europe and are considered potential vectors of Rift Valley fever virus, a virus not present but at risk of introduction on the continent. In this work, we analysed abundance data collected during West Nile virus (WNV) surveillance in northern Italy (Po Plain) via 292 CO2-baited traps to evaluate the distribution and density of these two non-target mosquitoes. We modelled the distribution and abundance of these two mosquito species in the surveyed area using two distinct spatial analysis approaches (geostatistical and machine learning), which yielded congruent results. Both species are more abundant close to the Po River than elsewhere, but Ae. caspius is present in the eastern and western parts of the plain, linked with the occurrence of rice fields and wetlands, while Ae. vexans is observed in the middle area of the plain. Presence and abundance data at the municipality level were obtained and made available through this work. This work demonstrates the importance of maintaining and improving entomological surveillance programs with an adequate sampling effort.

Challenges in Influenza Control and Surveillance in the Republic of Kazakhstan

The COVID-19 pandemic has significantly disrupted the circulation of influenza viruses in Kazakhstan, highlighting the vulnerabilities in the country’s public health infrastructure. This review critically examines the challenges faced in infiltrating and controlling influenza in Kazakhstan, particularly in light of the shifting epidemiological landscape post-pandemic. Key issues include the decline in influenza cases during the pandemic, which complicates the assessment of influenza epidemiology, vaccine effectiveness, and planning of vaccination campaigns. Although part of the Global Influenza Hospital Surveillance Network (GIHSN), Kazakhstan's surveillance systems face data collection, coordination, and public awareness gaps. The review discusses the prevalence of various influenza strains, the impact of zoonotic infections, and the necessity for improved monitoring frameworks. Additionally, the historical context of infectious disease control in Kazakhstan is explored, emphasising the need for enhanced international collaboration and targeted public health strategies. The findings underscore the importance of vaccination and robust surveillance to mitigate the risks of seasonal and pandemic influenza, advocating for a comprehensive approach to safeguard public health in Kazakhstan.

Circulating respiratory viruses including SARS-CoV-2 during 2021-2022 season in Tunisia: Epidemiological and dynamic changes

BackgroundChanging patterns in community respiratory virus activity were reported in different geographical locations during the COVID-19 pandemic. In this study, we aimed to assess the prevalence of circulating respiratory viruses, including SARS-CoV-2, during the season 2021-2022 in Tunisia. MethodsWe retrospectively enrolled 328 nasopharyngeal samples received at the Triage Center of Habib Bourguiba Hospital from patients with acute respiratory symptoms during September 2021-May 2022. All samples were screened for both SARS-CoV-2 and common respiratory viruses. This latter detection was performed using end-point multiplex RT-PCRs, Real-Time PCR, and AllplexTM Respiratory Panel 1 kit (Seegene) for Influenza Virus A (IFVA) and Respiratory Syncytial Virus (RSV) subtyping. ResultsAmong included patients, at least one viral pathogen was identified in 118 (35.9%) patients. The detection rate of SARS-CoV-2 was 21.6%. A low viral coinfection rate was observed (3.3%). The most prevalent pathogen among non-SARS-CoV-2 viruses was Enterovirus/Rhinovirus (HEV/HRV) (59.6%) followed by IFVA (15.3%) and Adenoviruses (ADV) (11.5%). Only IFVA H3N2 was found to circulate during the study period. A negative virus interaction was eventually induced by SARS-CoV-2, as it was shown by lower levels of activity of non-SARS-CoV-2 viruses (not exceeding 17.7%) while infections due to pandemic Omicron variants of concern became widespread. ConclusionsThis study highlights the relative return of community IFVA circulation during the 2021-2022 season in Tunisia. A negative viral interaction between SARS-CoV-2 and other respiratory viruses is highly suggested, which explains, in addition to the easing of COVID-19 restriction measures, the epidemiological changes in non-SARS-CoV-2 viruses circulation.

Ecological and Reproductive Cycles Drive Henipavirus Seroprevalence in the African Straw-Coloured Fruit Bat (Eidolon helvum).

Bats are known to host zoonotic viruses, including henipaviruses that cause high fatality rates in humans (Nipah virus and Hendra virus). However, the determinants of zoonotic spillover are generally unknown, as the ecological and demographic drivers of viral circulation in bats are difficult to ascertain without longitudinal data. Here we analyse serological data collected from African straw-coloured fruit bats (Eidolon helvum) in Ghana over the course of 2 years and across four sites, comprising three wild roosts and one captive colony. We focus on antibody affinity to five henipavirus antigens: Ghanaian bat henipavirus (GhV), Nipah virus (NiV), Hendra virus (HeV), Mojiang virus (MojV) and Cedar virus (CedV). In the wild roosts, we detected seasonal variations in henipavirus antibody binding, possibly associated with bat life-history cycles and migration patterns. In the captive colony, we identified increases in antibody affinity levels among pregnant bats, suggesting possible shifts in the immune system during pregnancy. These bats then pass maternal antibodies to their pups, which wane before antibody affinity levels rise later in life following initial infections and/or reactivation of latent infections. These results improve our understanding of the links between bat ecology and viral circulation, including for GhV, a locally-circulating African henipavirus.

Environmental and host factors underlying tick-borne virus infection in wild animals: Investigation of the emerging Yezo virus in Hokkaido, Japan

Yezo virus (YEZV) is an emerging tick-borne virus that causes acute febrile illness. It has been continuously reported in patients and ticks in Japan and China since its first identification in Hokkaido, Japan. While serological tests have demonstrated that YEZV infections are prevalent in wild animals, such as raccoons (Procyon lotor), the determinants of infection in wild animals remain largely unknown. We examined the prevalence of YEZV in invasive raccoons, native tanukis (raccoon dogs, Nyctereutes procyonoides albus), and ticks in six study areas in Hokkaido between 2018 and 2023 to identify ecological factors underlying YEZV infection in wild animals. YEZV RNA fragments were detected in 0.22% of the 1,857 questing ticks. Anti-YEZV antibodies were detected in 32 of the 514 (6.2%) raccoon serum samples and in 5 of the 40 (12.5%) tanuki serum samples. Notably, the seroprevalence in raccoons varied significantly in one of the study areas over the years, that is, 0.0%, 60.0%, and 28.6% in 2021, 2022, and 2023, respectively, implying the temporary emergence of YEZV microfoci. By analyzing the tick load and YEZV seropositivity in raccoons in a field-based setting, we found a positive correlation between adult Ixodes ovatus load and YEZV-antibody positivity, highlighting the importance of I. ovatus in YEZV infection in wild animals. We also explored the environmental and host factors influencing YEZV seropositivity in raccoons and tanukis and found that landscape factors, such as the size of forest area around the trap site, were crucial for YEZV seropositivity in these animals. The significant variables for YEZV seropositivity in raccoons were partially different from those affecting tick infestation intensity in raccoons. The present results extend our understanding of tick-borne virus circulation in the field, emphasizing the unique ecology of the emerging YEZV.